<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Dom操作</title>
</head>
<body>

    <input type="text"><button>搜索</button>
    <script>
        var ch = document.body.children[1];
        ch.style.color="red";
    </script>
    
</body>
</html>